Avoiding deepwater hazards using LWD acoustic data

摘要

Drilling expensive and challenging wells in deepwater requires significant pre-well planning to mitigate the risks. Understanding of the regional drilling hazards that nearby operators have encountered and correlating them to the current project must be done to gain a clear appreciation of potential problem hole sections. In a Gulf of Mexico deepwater well drilled by ENI, significant efforts were taken to evaluate the potential for a shallow-water flow in the top-hole section..Another operator in a nearby block had recently lost a well due to a shallow-water flow. The loss caused heightened concern among the asset team. An extensive pore-pressure analysis of the surface seismic data was performed for the current project. The analysis indicated a strong potential for a shallow-water flow also existed in this well. To build the best possible understanding of the pore pressure profile for the well, the surface seismic pressure analysis was taken much deeper than customary; in this case to the top of the salt. Pre-well pore-pressure models were constructed and confirmed ENI's surface seismic pore-pressure assessment As a result, real-time pore-pressure monitoring services were deemed essential to monitor the progress of the well and, with that information, make real-time adjustments to the drilling parameters (e.g., mud weight) as they became necessary.